THe present invention relates to turn-around devices for rod-shaped articles, such as filter rod sections or plain or filter-tipped cigarettes, cigars or cigarillos. More particularly, the invention relates to a device which is especially suited for turning end-for-end successive filter-tipped cigarettes, cigars or cigarillos in machines which produce filter-tipped articles of double unit length and comprise means for severing each article of double unit length midway between its ends to thus produce pairs of filter-tipped articles of unit length wherein the filter tips of each pair of articles are adjacent to each other. The invention will be described with reference to a turn-around device for filter cigarettes of unit length; however, it will be understood that the improved device can be used with equal advantage for tip turning of other types of rod-shaped articles which are transported sideways in the form of a row and must be turned or reoriented end-for-end.
A filter cigarette making machine normally produces a row of filter cigarettes of double unit length, and each such cigarette is thereupon severed midway across its filter tip of double unit length to yield two coaxial cigarettes of unit length. One cigarette of each pair must be turned or reoriented end-for-end in order to insure that the filter tips of all cigarettes face in the same direction. This is desirable for a number of reasons, i.e., to facilitate the testing of cigarettes for the density of free ends of their tobacco fillers as well as to insure that the filter tips of all cigarettes which enter the customary chargers or trays or are fed directly into the magazine of a packing machine face in the same direction.
German Offenlegungsschrift No. 1,901,618 discloses a turn-around device for filter cigarettes wherein a conveyor transports pairs of coaxial filter cigarettes of unit length in such a way that the filter tips of cigarettes forming a pair are adjacent to each other. The turn-around device further comprises a mechanism which causes one cigarette of each pair to travel along an arcuate circular path and to change its orientation by 180.degree. before the thus reoriented cigarette is redeposited onto the conveyor, preferably into an empty flute between two non-inverted cigarettes. The mechanism comprises first cigarette carriers in the form of suction heads which lift cigarettes to be turned off the conveyor and transport them along one-half of the aforementioned circular path with simultaneous reorientation by 90.degree.. The mechanism further comprises second cigarette carriers which accept partially reoriented cigarettes from successive first carriers and transport such cigarettes along the other half of the circular path with simultaneous reorientation by 90.degree. before the tip turned cigarettes are redeposited on the conveyor. The second carriers are mirror symmetrical to the first carriers, and each carrier is pivotable by a lever having a first end articulately connected to a rotary support and a second end travelling in a stationary circular guide groove. The center of the groove for the levers which support the first carriers is eccentric to the axis of the respective rotary support, and the position of the center of the groove for the levers which support the second carriers with respect to the corresponding rotary support is analogous. The eccentricity of the groove with respect to the corresponding rotary supports is selected with a view to effect partial reorientation of cigarettes during travel with the first carriers and to effect the remainder of reorientation during travel with the second carriers.
A drawback of the just described turn-around device is that the end portions of levers which travel in the guide grooves are subjected to extensive wear and to substantial deforming stresses. As a rule, the corresponding ends of the levers carry followers which roll along the surfaces bounding the respective grooves, and the ends of the levers must be free to swivel in the respective grooves. To this end, the followers are preferably spheres whose surfaces undergo extensive wear so that the useful life of such followers is extremely short. Furthermore, the frictional engagement between spherical followers and surfaces bounding the grooves produces substantial amounts of heat with attendant expansion of followers which are thereby likely to become stuck in the grooves, especially since the carriers must be guided with a high degree of accuracy so that the clearances between the grooves and the followers therein must be held to a minimum. The surfaces bounding the grooves surround the followers from three sides so that the dissipation of heat is negligible, and this further enhances the likelihood of jamming.